1. Field of the Invention
The present invention relates to an information recording medium such as a DVD, on which a large amount of information such as images, sound, etc. can be recorded densely, and a reproducing apparatus to reproduce the information recorded on the information recording medium.
2. Description of the Related Art
An LD (Laser Disk), a CD (Compact Disk), etc. are popular as an optical disc to record information such as images, sound, etc. thereon.
On such an LD or CD etc, image information and audio information are recorded together with time information, which represents a time to reproduce each of the image information and audio information on the basis of the reproduction starting point. Therefore, in the case of CD, it is possible not only to reproduce the audio information in order of the recording arrangement but also to reproduce only some pieces of audio information that the user wants to listen. Furthermore, it is possible to reproduce audio information in random order.
However, the user have no choice with respect to contents of images to be displayed or contents of sound to be reproduce. For example, when watching pictures or movies, the user cannot choose the subtitles. When listening music, the user cannot choose the sound, voice or language (e.g. lyrics). This is a disadvantage of the conventional optical disc, LD or CD. That is, the LD or CD does not has the capability of interactive selection or the capability that many choices are given to the user.
On the other hand, a DVD, which is a kind of optical disk, has been proposed and now actively developed. The DVD has the same size as that of the CD, and has a recording capacity that is about ten times as large as that of the CD. If such a DVD is used, a number of subtitles and a number of lyrics can be recorded on it, and it makes possible to allow the user to choose the subtitles or lyrics. That is, according to the DVD, it is possible to achieve the interactive selection and to give many choices to the user.
If audio information such as music etc. is recorded on the DVD, the audio information whose amount is as large as the total amount of audio information recorded on several CDs can be recorded on it, since the DVD has a large amount of recording capacity. Hereinafter, a DVD on which audio information is mostly recorded is referred to as an "audio DVD".
For example, if an audio DVD is produced with respect to one musician, all of the songs included in several CD albums produced by this musician can be recorded on this one audio DVD. Furthermore, it is possible to select several songs from these CD albums on the basis of a certain theme and add them as a song collection album onto the same audio DVD.
More concretely, if an audio DVD is produced with respect to the Beatles, all of the songs included in several CD albums produced by the Beatles can be recorded on this one audio DVD. Furthermore, it is possible to select several songs that the lead vocal is John Lennon from these CD albums and add them as "John Lennon Vocal Collection Album" onto the same audio DVD.
In this case, the same song is recorded doubly on one audio DVD. For example, the song, "Let It Be", is recorded as a song included in the album whose title is "Let It Be", and this song is further recorded as a song included in the "John Lennon Vocal Collection Album".
It is useless to record the same song more than one time. That is, recording the audio information having same contents onto one DVD is in vain.